Ink composition, inkjet recording system, and inkjet recording method

ABSTRACT

An ink composition is held in an ink container that is provided with an ink inlet through which the ink container can be refilled with the ink composition, and is used in a state in which the ink container is fitted into an inkjet recording device that includes a recording head having a nozzle hole that ejects the ink composition, the ink composition including a disperse dye, and at least one of a silicon-based surfactant and a fluorine-based surfactant, the ink composition having a surface tension of 22 to 30 mN/m.

Priority is claimed under 35 U.S.C. §119 to Japanese Application No.2012-246129 filed on Nov. 8, 2012 and under 35 U.S.C. §365 toPCT/JP2013/079850 filed on Nov. 5, 2013.

TECHNICAL FIELD

The present invention relates to an ink composition, an inkjet recordingsystem, and an inkjet recording method.

BACKGROUND ART

An inkjet recording device has been known that records an image or acharacter by ejecting a minute droplet of an ink composition from anozzle hole of a recording head so that the droplet adheres to arecording medium. An inkjet ink composition that includes a coloringmaterial, a surfactant, water, an organic solvent, and the like has beenknown as the ink composition.

Various types of performance are required for each element (e.g., inkcomposition, recording device, and recording medium) when implementingan inkjet recording process. For example, a measure that suppresses asituation in which air bubbles are formed in the ink compositioncontained in the inkjet recording device has been desired in order toprevent a situation in which the ink composition is ejected in anunstable way, and the recording quality deteriorates. Patent Literature1 (JP-A-11-048491), Patent Literature 2 (JP-A-11-048492), and PatentLiterature 3 (JP-A-11-048493) propose an inkjet printer that includes adeaeration mechanism in order to solve the above problem. PatentLiteratures 1 to 3 disclose removing gas dissolved in the ink using thedeaeration mechanism, and achieving stable ejection performance, forexample.

SUMMARY OF THE INVENTION Technical Problem

However, the methods disclosed in Patent Literatures 1 to 3 have aproblem in that the size of the inkjet recording device increases, andthe installation area or the like is limited, since it is necessary toprovide the inkjet recording device with the deaeration mechanism.

When the ink has been consumed by the inkjet recording device, and thevolume of the ink has decreased, the cartridge (hereinafter may bereferred to as “ink container”) is replaced with another cartridge, forexample. In this case, since the cartridge is filled with the ink in astate in which the ink does not easily come in contact with the air, itis possible to suppress a situation in which gas is dissolved in theink, and suppress formation of air bubbles.

In recent years, since the amount of ink composition consumed hasincreased along with an increase in the amount of recording using aninkjet recording device, it has been necessary to frequently exchangethe cartridge. In order to reduce the cartridge exchange frequency,attempts have been made that increase the size of the cartridge, orrefill the cartridge with the ink composition, for example.

However, the area of contact between the ink composition and gas (i.e.,the area of the gas-liquid interface) within the cartridge increases ifthe size of the cartridge is increased. When the cartridge is refilledwith the ink composition from the outside, the ink composition easilycomes in contact with the air when refilling the cartridge with the inkcomposition. Therefore, gas may be easily dissolved in the inkcomposition, and air bubbles may be formed in the ink composition.

An object of several aspects of the invention is to provide an inkcomposition from which air bubbles can be promptly removed when airbubbles have been formed in the ink composition. Another object ofseveral aspects of the invention is to provide an ink composition fromwhich air bubbles can be promptly removed even when the ink compositionis held in an ink container that has such a shape that the inkcomposition easily comes in contact with the air. A further object ofseveral aspects of the invention is to provide an inkjet recordingsystem and an inkjet recording method that ensure that air bubbles canbe removed from an ink composition when air bubbles have been formed inthe ink composition.

Solution to Problem

The invention was conceived in order to solve at least some of the aboveproblems (objects), and may be implemented as described below (see thefollowing aspects or application examples).

APPLICATION EXAMPLE 1

According to one aspect of the invention, an ink composition is held inan ink container that is provided with an ink inlet through which theink container can be refilled with the ink composition, and is used in astate in which the ink container is fitted into an inkjet recordingdevice that includes a recording head having a nozzle hole that ejectsthe ink composition, the ink composition including a disperse dye, andat least one of a silicon-based surfactant and a fluorine-basedsurfactant, the ink composition having a surface tension of 22 to 30mN/m.

According to Application Example 1, air bubbles can be promptly removedfrom the ink composition when air bubbles have been formed in the inkcomposition. This makes it possible to suppress a situation in which airbubbles remain in the ink container, the recording head, and the like,and ensure ejection stability.

APPLICATION EXAMPLE 2

In the ink composition according to Application Example 1, the nozzlehole may have a part in which the area of the cross section of thenozzle hole perpendicular to the ink composition ejection directiondecreases discontinuously in the ink composition ejection direction.

According to Application Example 2, since air bubbles can be promptlyremoved from the ink composition when air bubbles have been formed inthe ink composition, it is possible to suppress a situation in which airbubbles remain even when the nozzle hole has a shape that isdisadvantageous for discharging or moving air bubbles.

APPLICATION EXAMPLE 3

In the ink composition according to Application Example 1 or 2, the inkcontainer may satisfy the relationship “area of liquid surface at afilling ratio of 5% <area of liquid surface at a filling ratio of morethan 5%” when the ink container is fitted into the inkjet recordingdevice in a usage state, the filling ratio being the ratio of the volumeof the ink composition with which the ink container is filled to theinternal volume of the ink container, and the liquid surface being thegas-liquid interface of the ink composition that is formed inside theink container.

Even when the ink container has such a shape that the area of contactbetween the ink composition and gas (i.e., the area of the gas-liquidinterface) satisfies the above relationship, and gas may be dissolved inthe ink composition, since air bubbles can be promptly removed from theink composition, it is possible to ensure sufficient ejection stability.

APPLICATION EXAMPLE 4

The ink composition according to any one of Application Examples 1 to 3may have a surface tension of 22 to 25 mN/m.

According to Application Example 4, air bubbles can be removed morepromptly when air bubbles have been formed in the ink composition. Thismakes it possible to suppress a situation in which air bubbles remain inthe ink container, the recording head, and the like, and ensure betterejection stability.

APPLICATION EXAMPLE 5

The ink composition according to any one of Application Examples 1 to 4may further include a penetrant having an HLB value of 17 to 30.

According to Application Example 5, it is possible to improvepenetration of the ink composition during printing while suppressing adeterioration in the dispersion state of the disperse dye.

APPLICATION EXAMPLE 6

The ink composition according to any one of Application Examples 1 to 5may include a penetrant having an HLB value of less than 17 in a ratioof 1 mass % or less based on the total amount of the ink composition.

According to Application Example 6, it is possible to improvepenetration of the ink composition during printing while suppressing adeterioration in the dispersion state of the disperse dye.

APPLICATION EXAMPLE 7

According to another aspect of the invention, an inkjet recording systemincludes: an ink composition that includes a disperse dye, and at leastone of a silicon-based surfactant and a fluorine-based surfactant; anink container that is provided with an ink inlet through which the inkcontainer can be refilled with the ink composition; and an inkjetrecording device that includes a recording head having a nozzle holethat ejects the ink composition, the ink composition having a surfacetension of 22 to 30 mN/m.

According to the inkjet recording system, since air bubbles can bepromptly removed from the ink composition when air bubbles have beenformed in the ink composition, it is possible to suppress a situation inwhich air bubbles remain in the inkjet recording system, and ensure goodejection stability.

APPLICATION EXAMPLE 8

According to another aspect of the invention, an inkjet recording methodincludes: filling an ink container with an ink composition, the inkcomposition including a disperse dye, and at least one of asilicon-based surfactant and a fluorine-based surfactant, and having asurface tension of 22 to 30 mN/m, and the ink container being providedwith an ink inlet through which the ink container can be refilled withthe ink composition; fitting the ink container into an inkjet recordingdevice that includes a recording head having a nozzle hole that ejectsthe ink composition; and ejecting the ink composition from the nozzlehole so that the ink composition adheres to a medium.

According to the inkjet recording method, since air bubbles can bepromptly removed from the ink composition when air bubbles have beenformed in the ink composition, it is possible to ensure good ejectionstability, and implement a good recording process that can reliably formthe entire image on the medium, for example.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic cross-sectional view illustrating an example of anozzle hole formed in a nozzle plate.

FIG. 2 is a perspective view illustrating an example of an inkjetrecording device into which an ink container is fitted.

FIG. 3 is a perspective view illustrating an example of an ink containerin a state in which a slider is separated.

FIG. 4 is an exploded perspective view illustrating an example of an inkcontainer.

FIG. 5 is a side view schematically illustrating a state in which a filmis bonded to a holder case.

FIG. 6 is a schematic cross-sectional view illustrating an example of anink container.

DESCRIPTION OF EMBODIMENTS

Several exemplary embodiments of the invention are described below. Thefollowing exemplary embodiments illustrate an example of the invention.The invention is not limited to the following exemplary embodiments. Theinvention includes various modifications that can be practiced withoutdeparting from the scope of the invention. Note that all of the elementsdescribed below in connection with the following exemplary embodimentsshould not necessarily be taken as essential elements of the invention.

1. Ink Composition

An ink composition according to one embodiment of the invention includesa disperse dye, and at least one of a silicon-based surfactant and afluorine-based surfactant.

1.1. Disperse Dye

The ink composition according to one embodiment of the inventionincludes the disperse dye. The disperse dye is suitably used to dyehydrophobic synthetic fibers such as polyester fibers, nylon fibers, andacetate fibers, and is a compound that is insoluble or scarcely solublein water.

The disperse dye included in the ink composition according to oneembodiment of the invention is not particularly limited. Specificexamples of the disperse dye include the following.

Examples of a yellow disperse dye include C.I. Disperse Yellow 3, 4, 5,7, 9, 13, 23, 24, 30, 33, 34, 42, 44, 49, 50, 51, 54, 56, 58, 60, 63,64, 66, 68, 71, 74, 76, 79, 82, 83, 85, 86, 88, 90, 91, 93, 98, 99, 100,104, 108, 114, 116, 118, 119, 122, 124, 126, 135, 140, 141, 149, 160,162, 163, 164, 165, 179, 180, 182, 183, 184, 186, 192, 198, 199, 202,204, 210, 211, 215, 216, 218, 224, 227, 231, 232, and the like. Examplesof an orange disperse dye include C.I. Disperse Orange 1, 3, 5, 7, 11,13, 17, 20, 21, 25, 29, 30, 31, 32, 33, 37, 38, 42, 43, 44, 45, 46, 47,48, 49, 50, 53, 54, 55, 56, 57, 58, 59, 61, 66, 71, 73, 76, 78, 80, 89,90, 91, 93, 96, 97, 119, 127, 130, 139, 142, and the like. Examples of ared disperse dye include C.I. Disperse Red 1, 4, 5, 7, 11, 12, 13, 15,17, 27, 43, 44, 50, 52, 53, 54, 55, 56, 58, 59, 60, 65, 72, 73, 74, 75,76, 78, 81, 82, 86, 88, 90, 91, 92, 93, 96, 103, 105, 106, 107, 108,110, 111, 113, 117, 118, 121, 122, 126, 127, 128, 131, 132, 134, 135,137, 143, 145, 146, 151, 152, 153, 154, 157, 159, 164, 167, 169, 177,179, 181, 183, 184, 185, 188, 189, 190, 191, 192, 200, 201, 202, 203,205, 206, 207, 210, 221, 224, 225, 227, 229, 239, 240, 257, 258, 277,278, 279, 281, 288, 298, 302, 303, 310, 311, 312, 320, 324, 328, and thelike. Examples of a violet disperse dye include C.I. Disperse Violet 1,4, 8, 23, 26, 27, 28, 31, 33, 35, 36, 38, 40, 43, 46, 48, 50, 51, 52,56, 57, 59, 61, 63, 69, 77, and the like. Examples of a green dispersedye include C.I. Disperse Green 9 and the like. Examples of a browndisperse dye include C.I. Disperse Brown 1, 2, 4, 9, 13, 19, and thelike. Examples of a blue disperse dye include C.I. Disperse Blue 3, 7,9, 14, 16, 19, 20, 26, 27, 35, 43, 44, 54, 55, 56, 58, 60, 62, 64, 71,72, 73, 75, 79, 81, 82, 83, 87, 91, 93, 94, 95, 96, 102, 106, 108, 112,113, 115, 118, 120, 122, 125, 128, 130, 139, 141, 142, 143, 146, 148,149, 153, 154, 158, 165, 167, 171, 173, 174, 176, 181, 183, 185, 186,187, 189, 197, 198, 200, 201, 205, 207, 211, 214, 224, 225, 257, 259,267, 268, 270, 284, 285, 287, 288, 291, 293, 295, 297, 301, 315, 330,333, and the like. Examples of a black disperse dye include C.I.Disperse Black 1, 3, 10, 24, and the like.

These disperse dyes may be used either alone or in combination.

Examples of a commercially available product of the disperse dye include

Oracet Yellow 8GF (manufactured by Ciba-Geigy, C.I. Disperse Yellow 82),Aizen Sot Yellow 5 (manufactured by Hodogaya Chemical Co., Ltd., C.I.Disperse Yellow 3), Sumiplast Yellow HLR (manufactured by SumitomoChemical Co., Ltd., C.I. Disperse Yellow 54), Kayaset Yellow A-G(manufactured by Nippon Kayaku Co., Ltd., C.I. Disperse Yellow 54),Diaresin Yellow H2G (manufactured by Mitsubishi

Chemical Corporation, C.I. Disperse Yellow 160), Oil Yellow 54(manufactured by Chuo Synthetic Chemical Co., Ltd., C.I. Disperse Yellow54), Diaresin Red H (manufactured by Mitsubishi Chemical Corporation,C.I. Disperse Red 5), Sumiplast Red B-2 (manufactured by SumitomoChemical Co., Ltd., C.I. Disperse Red 191), Kayaset Red B (manufacturedby Nippon Kayaku Co., Ltd., C.I. Disperse Red 60),

Filester violet BA (manufactured by Ciba-Geigy, C.I. Disperse Violet57), Plast Red 8335 (manufactured by Arimoto Chemical Co., Ltd., C.I.Disperse Violet 17), Plast Red 8375 (manufactured by Arimoto ChemicalCo., Ltd., C.I. Disperse Red 60), Plast Blue 8516 (manufactured byArimoto Chemical Co., Ltd., C.I. Disperse Blue 14), and the like.

The content of the disperse dye in the ink composition according to oneembodiment of the invention is preferably 0.1 to 10 mass %, morepreferably 0.25 to 9 mass %, and particularly preferably 1 to 8 mass %,from the viewpoint of dyeability and the solubilization capability ofthe disperse dye.

1.2. Surfactant

The ink composition according to one embodiment of the inventionincludes at least one of the silicon-based surfactant and thefluorine-based surfactant.

One of the effects of these surfactants is to adjust the surface tensionof the ink composition, and removes (discharges) air bubbles from theink composition when air bubbles have been formed in the inkcomposition. The surfactants described below may be used either alone orin combination. The surface tension of the ink composition can beappropriately adjusted by changing the type and the composition of thesurfactant.

The total content of at least one of the silicon-based surfactant andthe fluorine-based surfactant in the ink composition is preferably 0.05to 1.5 mass %, more preferably 0.05 to 1.2 mass %, and particularlypreferably 0.1 to 1 mass %.

When the content of the surfactant is within the above range, it ispossible to easily adjust the surface tension of the ink composition to22 to 30 mN/m.

1.2.1. Silicon-Based Surfactant

Examples of the silicon-based surfactant include a surfactant having apolysiloxane structure that includes a siloxane unit. A hydrogen atom,an unmodified hydrocarbon group, an ether-modified hydrocarbon group, apolyester-modified hydrocarbon group, an epoxy-modified hydrocarbongroup, an amine-modified hydrocarbon group, a carboxyl-modifiedhydrocarbon group, a fluorine-modified hydrocarbon group, analkyloxy-modified hydrocarbon group, a mercapto-modified hydrocarbongroup, a (meth)acrylic-modified hydrocarbon group, a phenol-modifiedhydrocarbon group, a phenyl-modified hydrocarbon group, acarbinol-modified hydrocarbon group, or an aralkyl-modified hydrocarbongroup may be included in the side chain of the polysiloxane. The sidechain of the polysiloxane may preferably include an unmodifiedhydrocarbon group, an ether-modified hydrocarbon group, or apolyester-modified hydrocarbon group.

Specific examples of a silicon-based surfactant that includes adimethylsiloxane unit include BYK-347 and BYK-348 (manufactured by BYKJapan KK); and the like. Specific examples of a polyether-modifiedorganosiloxane include BYK-378, BYK-333, and BYK-337 (manufactured byBYK Japan KK); and the like.

When the silicon-based surfactant is used alone, the content of thesilicon-based surfactant in the ink composition is 0.01 to 1.5 mass %,and preferably 0.05 to 1.2 mass %.

1.2.2. Fluorine-Based Surfactant

Examples of the fluorine-based surfactant that can be applied to the inkcomposition according to one embodiment of the invention include asurfactant in which some or all of the hydrogen atoms bonded to a carbonatom included in a hydrophobic group are substituted with a fluorineatom. Specific examples of the fluorine-based surfactant include aperfluoroalkylsulfonic acid salt, a perfluoroalkylcarboxylic acid salt,a perfluoroalkylphosphoric ester, a perfluoroalkyl ethylene oxideadduct, a perfluoroalkylbetaine, a perfluoroalkylamine oxide compound,and the like.

It is preferable to use a fluorine-based surfactant that includes aperfluoroalkyl group or a perfluoroalkenyl group in the molecule. Thefluorine-based surfactant may be an anionic fluorine-based surfactant, anonionic fluorine-based surfactant, or an amphoteric fluorine-basedsurfactant.

The fluorine-based surfactant is commercially available as Megafac(manufactured by DIC Corporation), Surflon (manufactured by Asahi GlassCo., Ltd.), Novec (manufactured by Sumitomo 3M Ltd.), Zonyls(manufactured by E. I. du Pont de Nemours and Company (DuPont)), andFtergent (manufactured by NEOS Co., Ltd.).

Specific examples of a commercially available product of thefluorine-based surfactant include Surflon S-211, Surflon S-131, SurflonS-132, Surflon S-141, Surflon S-144, and Surflon S-145 (manufactured byAsahi Glass Co., Ltd.); Ftergent 100 and Ftergent 150 (manufactured byNEOS Co., Ltd.); Megafac F477 (manufactured by DIC Corporation);FC-170C, FC-430, and Fluorad FC4430 (manufactured by Sumitomo 3M Ltd.);FSO, FSO-100, FSN, FSN-100, and FS-300 (manufactured by DuPont); FT-250and FT-251 (manufactured by NEOS Co., Ltd.); and the like.

These fluorine-based surfactants may be used either alone or incombination.

When the fluorine-based surfactant is used alone, the content of thefluorine-based surfactant in the ink composition is 0.01 to 1.2 mass %,preferably 0.05 to 1 mass %, and more preferably 0.1 to 0.75 mass %.

1.3. Additional Component

The ink composition according to one embodiment of the invention mayappropriately include water, a dispersant, a penetrant, and anadditional additive.

1.3.1. Water

The ink composition according to one embodiment of the invention mayinclude water. Water may be used as the main medium for the inkcomposition. Water is a component that adheres to a recording medium,and evaporates due to drying. It is preferable to use water from whichionic impurities have been removed as much as possible (e.g., pure wateror ultrapure water such as ion-exchanged water, water purified byultrafiltration, water purified by reverse osmosis, or distilled water).It is preferable to use water sterilized by UV irradiation, addition ofhydrogen peroxide, or the like since the growth of fungi and bacteriacan be prevented when a pigment dispersion, or an ink compositionprepared using the pigment dispersion, is stored for a long time.

1.3.2. Dispersant

The ink composition according to one embodiment of the invention mayinclude a dispersant for dispersing the disperse dye. A formaldehydecondensate of an aromatic sulfonic acid salt may suitably be used as thedispersant. Specific examples of the formaldehyde condensate of anaromatic sulfonic acid salt include a formaldehyde condensate of asodium aromatic sulfonate, a formaldehyde condensate of a potassiumaromatic sulfonate, a formaldehyde condensate of a sodiumalkylarylsulfonate, and the like. Examples of a commercially availableproduct of the formaldehyde condensate of an aromatic sulfonic acid saltinclude Lavelin (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.)(formaldehyde condensate of sodium methylnaphthalenesulfonate).

When adding the formaldehyde condensate of an aromatic sulfonic acidsalt to the ink composition according to one embodiment of the inventionas the dispersant, the content of the formaldehyde condensate of anaromatic sulfonic acid salt in the ink composition is preferably 1 to 10mass %, more preferably 2 to 9 mass %, and particularly preferably 3 to8 mass %, from the viewpoint of capability to disperse the disperse dye.

1.3.3. Penetrant

The ink composition according to one embodiment of the invention mayinclude a penetrant. It is preferable to use a penetrant that canimprove penetration of the disperse dye into the medium during printingwhile maintaining the dispersion state of the disperse dye. Examples ofsuch a penetrant include a penetrant that has a high HLB value.

The term “HLB value” used herein refers to a value calculated using thefollowing expression.

HLB value=10×(IV/OV)

where, IV/OV is the ratio (JOB value) of an inorganic value (IV) to anorganic value (OV) based on the organic conceptual diagram.

The organic conceptual diagram is obtained by mapping organicity(covalent bonding capability) based on the number of carbon atoms andinorganicity (ion bonding capability) based on a substituent onto aCartesian coordinate sysyem having an organic axis and an inorganicaxis, and has been known as an index that predicts the properties of anorganic compound. The organic value of one carbon atom is 20. The totalinorganic value (IV) and the total organic value (OV) are calculatedfrom the structure of an organic compound using the organic value andthe inorganic value of each substituent included in the organic compound(see “New Technology and Application of Dispersion & Emulsion Systems”,edited by Kunio Furusawa, Technosystem Co., Ltd., June 20, 2006, p.166ff).

An inorganic value/organic value calculation example and a specificexample of the HLB value are described below using triethylene glycolmonomethyl ether as an example. Triethylene glycol monomethyl etherincludes seven carbon atoms, one OH group, and three ether linkages.When calculating the inorganic value of a primary alcohol that includesa plurality of ethylene glycol chains, the inorganic value of the firstether linkage is calculated to be 20, and the inorganic value of each ofthe other two ether linkages is calculated to be 75. Therefore, theorganic value of triethylene glycol is 20×7=140, the inorganic value oftriethylene glycol is 100+20+150=270, the IOB value is 270/140=1.93, andthe HLB value is 10×1.93=19.3.

The HLB value of the penetrant that may be included in the inkcomposition according to one embodiment of the invention is preferably17 to 30, and more preferably 18 to 25. When the penetrant has an HLBvalue within the above range, the penetrant has sufficiently highhydrophilicity, and the dispersion state of the disperse dye is rarelyimpaired. This makes it possible to improve penetration into a fabriccloth and the like, and provide the ink composition with storagestability. Examples of the penetrant having an HLB value of 17 to 30include triethylene glycol monomethyl ether (HLB=19.3), diethyleneglycol monomethyl ether (HLB=19.5), 1,2-pentanediol (HLB=20.0), and1,2-butanediol (HLB=25.0).

Among these, triethylene glycol monomethyl ether is preferable.

The content of the penetrant having an HLB value of 17 to 30 in the inkcomposition according to one embodiment of the invention is preferably 1to 15 mass %, and more preferably 2 to 10 mass %.

These penetrants may be used either alone or in combination. The inkcomposition according to one embodiment of the invention may include apenetrant having an HLB value of less than 17. The penetrant having anHLB value of less than 17 exhibits an excellent penetration capabilityinto a fabric cloth, but hydrophobicity becomes predominant overhydrophilicity to some extent. Therefore, the penetrant having an HLBvalue of less than 17 in the ink composition is preferably adjusted to17 mass % or less so that the dispersion state of the disperse dye isnot impaired.

Examples of the penetrant having an HLB value of less than 17 includetriethylene glycol monobutyl ether (HLB=13.5), 1,2-hexanediol(HLB=16.7), and the like.

1.3.4. Additional Additive

The ink composition according to one embodiment of the invention mayinclude a pH-adjusting agent, a chelating agent (e.g., ethylenediaminetetraacetate (EDTA)), a preservative, a fungicide, a rust preventive,and the like in addition to the above components as long as thedispersibility of the disperse dye is not impaired.

Note that it is preferable that the ink composition according to oneembodiment of the invention does not include an acetylene glycol-basedsurfactant. Since an acetylene glycol-based surfactant has low watersolubility, or includes a solvent having a small HLB value as asolubilizing agent, the dispersibility of the disperse dye may beimpaired, and the storage stability of the ink composition maydeteriorate.

1.4. Surface Tension

The ink composition according to one embodiment of the invention has asurface tension of 22 to 30 mN/m. The surface tension of the inkcomposition may be measured using a surface tensiometer (“CBVP-Z”manufactured by Kyowa Interface Science Co., Ltd.), for example.

The ink composition according to one embodiment of the invention may beprepared to have a surface tension of 22 to 25 mN/m. In this case, airbubbles can be removed more promptly when air bubbles have been formedin the ink composition. This makes it possible to suppress a situationin which air bubbles remain in the ink container, the recording head,and the like, and ensure better ejection stability.

The surface tension of the ink composition according to one embodimentof the invention can be adjusted by adjusting the amounts of thedisperse dye, the surfactant, and an optional additional component. Inparticular, it is effective to adjust the type and the amount of thesurfactant since it is possible to effectively adjust the surfacetension of the ink composition.

1.5. Advantageous Effects

Since the ink composition according to one embodiment of the inventionhas a surface tension of 22 to 30 mN/m, air bubbles can be promptlyremoved from the ink composition when air bubbles have been formed inthe ink composition. This makes it possible to suppress a situation inwhich air bubbles remain in the ink container, the recording head, andthe like, and ensure good ejection stability, even when the inkcomposition is held in an ink container having such a shape that the inkcomposition easily comes in contact with the air.

1.6. Application of Ink Composition

The ink composition according to one embodiment of the invention is heldin an ink container that is provided with an ink inlet through which theink container can be refilled with the ink composition, and is used in astate in which the ink container is fitted into an inkjet recordingdevice that includes a recording head having a nozzle hole that ejectsthe ink composition.

Since air bubbles can be promptly removed (discharged) from the inkcomposition according to one embodiment of the invention when airbubbles have been formed on the ink composition, the above advantageouseffects are achieved remarkably when the ink composition easily comes incontact with the air (see the inkjet recording device described below).

2. Inkjet Recording Device

An inkjet recording device according to one embodiment of the inventionincludes at least a recording head. The inkjet recording device isconfigured so that the ink container described later can be fitted intothe inkjet recording device. An ink composition contained in the inkcontainer is ejected from the recording head so that the ink compositionadheres to a predetermined medium.

The inkjet recording device may be a serial inkjet recording device, ormay be a line inkjet recording device. The serial inkjet recordingdevice and the line inkjet recording device are provided with arecording head, and configured so that a predetermined volume (mass) ofa droplet of an ink composition can be ejected from a nozzle hole of therecording head at a predetermined timing while changing the relativepositional relationship between the medium and the recording head sothat the ink composition adheres to the recording surface of the mediumto form a predetermined image.

The inkjet recording method is not particularly limited as long as adroplet of the ink composition can be ejected from the nozzle hole ofthe recording head so that the droplet adheres to the medium. Examplesof the inkjet recording method include an electrostatic suction inkjetrecording method, an inkjet recording method that ejects an ink dropletusing a pump pressure, an inkjet recording method that utilizes apiezoelectric device, an inkjet recording method that foams a liquid inkby heating using a micro-electrode to eject an ink droplet, and thelike.

The inkjet recording device may appropriately include a housing, arecording head carriage mechanism, a roller, a driver section, a controlsection, a sensor, a medium feeding mechanism, a tray, an operationpanel, and the like in addition to the recording head.

2.1. Recording Head

The recording head includes an ink inlet through which the inkcomposition is introduced, a mechanism that ejects the ink composition,and a nozzle hole that ejects the ink composition. The ink inlet can beconnected to the ink container described later, and the ink compositioncontained in the ink container is introduced into the recording head.The mechanism that ejects the ink composition is a pressure chamber forwhich the internal volume is changed using a piezo element, for example.The mechanism that ejects the ink composition can apply pressure to theink composition. The ink composition to which pressure has been appliedin the pressure chamber is ejected from the nozzle hole toward apredetermined medium.

The recording head may include a plurality of members such as a nozzleplate, a pressure chamber-forming substrate, a piezo substrate, an inkchannel-forming substrate, and a sub-tank. The nozzle hole may be formedin the nozzle plate, for example.

The nozzle hole allows the ink composition to flow in the ejectiondirection.

The nozzle hole is formed as a channel that is narrower than thepressure chamber so that the ink composition pressurized in the pressurechamber can be easily ejected in the form of a droplet.

The shape of the nozzle hole is not particularly limited. The nozzlehole may extend in the ink composition ejection direction, and have acolumnar shape, a circular truncated cone shape, an elliptical columnarshape, a prismatic shape, a truncated pyramidal shape, or a combinationthereof.

When the nozzle plate is made of a metal, the nozzle hole may be formedby punching the nozzle plate, for example. When the nozzle plate is madeof silicon, the nozzle hole may be formed by anisotropic etching thatutilizes an etching mask and an etchant, for example. When the nozzleplate is made of silicon, and the nozzle hole is formed by anisotropicetching, the accuracy of the shape of the nozzle hole is improved ascompared with the case of forming the nozzle hole by punching. It isalso possible to form a plurality of nozzle holes at a reduced interval.Therefore, it is preferable to form the nozzle plate using silicon whenit is desired to improve the resolution of the recording head.

When the nozzle plate is made of silicon, and the nozzle hole is formedby anisotropic etching, the nozzle hole may be formed to have a shapeobtained by stacking two columns that differ in diameter, by utilizingthe effect of anisotropic etching, for example. Specifically, the nozzlehole may be formed so that the nozzle hole has a columnar shape on theside of the pressure chamber, and has a columnar shape having a smallerdiameter on the side opposite to the pressure chamber. In such a case,the diameter of the nozzle hole may change discontinuously. In otherwords, the nozzle hole may have a part in which the area of the crosssection of the nozzle hole perpendicular to the ink composition ejectiondirection decreases discontinuously in the ink composition ejectiondirection. When the nozzle hole is formed to have a prismatic shape, thenozzle hole may also have a shape in which the area of the cross sectionof the nozzle hole perpendicular to the ink composition ejectiondirection decreases discontinuously in the ink composition ejectiondirection.

It is preferable to form the nozzle plate to have a thickness of 50micrometers or more in order to produce the nozzle plate in a stablemanner, for example. In this case, it is preferable to form the nozzlehole to have a shape in which the area of the cross section of thenozzle hole perpendicular to the ink composition ejection directiondecreases discontinuously in the ink composition ejection direction. Itis possible to eject a droplet of the ink composition at a higher speedby reducing the diameter of the nozzle hole on the side where the inkcomposition is ejected. If the nozzle hole is formed to have a shape inwhich the area of the cross section of the nozzle hole does not decreasediscontinuously while merely reducing the diameter of the nozzle hole,the flow resistance of the nozzle hole may increase to a large extent.It is possible to eject an ink droplet at a speed that ensures that theink droplet reaches the recording medium in a stable manner, and providean appropriate flow resistance, by forming the nozzle hole to have ashape in which the area of the cross section of the nozzle holedecreases discontinuously.

FIG. 1 is a schematic cross-sectional view illustrating an example ofsuch a nozzle hole. In the example illustrated in FIG. 1, a nozzle hole2 is formed in a nozzle plate 1, and the area of the cross section ofthe nozzle hole 2 decreases discontinuously in the ink compositionejection direction in the vicinity of the center of the nozzle plate 1in the thickness direction (see the boundary part 3). When the nozzlehole 2 has the shape illustrated in FIG. 1 in which the area of thecross section of the nozzle hole 2 decreases discontinuously (see theboundary part 3), it is possible to cause the ink composition to form ameniscus in a stable manner even when a printing process is performed ata high speed of 70 ppm (pages per minute) or more.

When the nozzle hole 2 has the shape illustrated in FIG. 1 in which thearea of the cross section of the nozzle hole 2 decreases discontinuously(see the boundary part 3), the line of flow may easily become unstablewhen the ink composition flows through the boundary part 3. Therefore,when air bubbles have been formed in the ink composition, the airbubbles tend to remain around an accumulation part 5 illustrated inFIG. 1. This may impair the ejection stability of the ink composition.However, since air bubbles can be promptly removed (discharged) from theink composition according to one embodiment of the invention, theejection stability of the ink composition is remarkably improved whenthe recording head has a nozzle hole having the above shape.

3. Ink Container

The ink composition according to one embodiment of the invention is heldin an ink container. The ink container includes an ink inlet throughwhich the ink container can be refilled with the ink composition. An inkcontainer according to a first embodiment and an ink container accordingto a second embodiment are described below.

3.1. First Embodiment

An ink container 21 according to the first embodiment, and an example ofan inkjet recording device (hereinafter may be referred to as “printer”)that utilizes the ink composition supplied from the ink container 21,are described below with reference to the drawings.

FIG. 2 is a perspective view illustrating an inkjet recording device 11into which the ink container 21 according to the first embodiment isfitted. FIG. 3 is a perspective view illustrating the ink container 21according to the first embodiment in a state in which a slider 34 isseparated. FIG. 4 is an exploded perspective view illustrating the inkcontainer 21 according to the first embodiment. FIG. 5 is a side viewschematically illustrating the ink container 21 according to the firstembodiment in a state in which a film 133 is bonded to a holder case130.

As illustrated in FIG. 2, the inkjet recording device 11 includes a leg13 to which wheels 12 are attached at the lower end, and a main body 14that is formed approximately in the shape of a rectangularparallelepiped, and is positioned on the leg 13. Note that a directionalong the gravitational direction is referred to as a vertical directionZ, and the longitudinal direction of the main body 14 that intersectsthe vertical direction Z (perpendicularly intersects the verticaldirection Z in the first embodiment) is referred to as a transversedirection X. A direction that intersects both the vertical direction Zand the transverse direction X (perpendicularly intersects both thevertical direction Z and the transverse direction X in the firstembodiment) is referred to as a depth direction Y.

As illustrated in FIG. 2, a feeder 15 that protrudes upward is providedin the rear part of the main body 14. A cylindrical roll R of paper S(long medium) is provided inside the feeder 15. A housing 16 forms theexterior of the main body 14, and an inlet 17 for introducing the paperS fed from the feeder 15 into the housing 16 is formed at a position onthe front side of the feeder 15.

An outlet 18 for discharging the paper S from the housing 16 is formedon the front side of the main body 14. A medium feeding mechanism (notillustrated in the drawings) that feeds the paper S fed from the feeder15 from the inlet 17 toward the outlet 18 is provided inside the housing16. A medium-receiving unit 19 that receives the paper S discharged fromthe outlet 18 is provided on the front side of the main body 14 at aposition lower than the outlet 18.

An operation panel 20 that allows the user to perform a settingoperation and an input operation is provided on the upper side of themain body 14 at one end (the right end in FIG. 2) in the transversedirection X that is situated outside the feeding path of the paper S.The ink container 21 that can hold the ink composition is secured on thelower part of the main body 14 at one end (the right end in FIG. 2) inthe transverse direction X that is situated outside the feeding path ofthe paper S.

A plurality of ink containers 21 (four ink containers 21 in the firstembodiment) are provided corresponding to the type and the color of theink composition. The plurality of ink containers 21 are arranged side byside in the transverse direction X to form an ink container unit 22.Note that the ink container unit 22 has an exposed part that is situatedon the front side (outer side) of the main body 14 in a state in whicheach ink container 21 is secured on the main body 14. Each side of theexposed part of the ink container unit 22 in the transverse direction X,and the lower side of the exposed part of the ink container unit 22 inthe vertical direction Z, are covered with a frame member 23 that issecured on the main body 14, and has an approximately U-shapedcross-sectional shape.

A carriage 25 that holds a recording head 24 provided inside the housing16 so that the carriage 25 can reciprocate in the transverse direction X(i.e., main scan direction). An ink supply mechanism (not illustrated inthe drawings) for supplying the ink composition contained in the inkcontainer 21 to the recording head 24 is provided inside the housing 16.A recording process (printing process) is performed by ejecting adroplet of the ink composition from the recording head 24 toward thepaper S that is fed by the medium feeding mechanism, and the inkcontained in the ink container 21 is consumed by ejecting the droplet ofthe ink composition. In the first embodiment, the ink container 21 isused in a state in which the ink container 21 is fitted to the framemember 23 of the inkjet recording device 11, and secured on the inkjetrecording device 11.

As illustrated in FIG. 3, the ink container 21 according to the firstembodiment includes an ink holder 33 that holds the ink, and a slider 34that is disposed on the ink holder 33 in the antigravitational direction(vertical direction).

The ink holder 33 is formed in the shape of a rectangular parallelepiped(that is formed approximately in the shape of the letter “L” in a sideview) that extends in the longitudinal direction (depth direction Y)that perpendicularly intersects the longitudinal direction of the mainbody 14 approximately in the horizontal direction, and has a fixed widthin the lateral direction (transverse direction X) that perpendicularlyintersects the longitudinal direction approximately in the horizontaldirection. Specifically, the ink holder 33 includes a first holdersection 37 that has an approximately square side shape when viewed inthe lateral direction (transverse direction X), and a second holdersection 38 that is situated on the rear side of the first holder section37, and has an approximately rectangular shape that is long in the depthdirection Y Flat sections 41 and 42 that continuously extend in thelongitudinal direction (depth direction Y) without a step are formed oneither end of the upper side 39 of the ink holder 33 in the lateraldirection, and the slider 34 can slide along the flat sections 41 and42. The lower side 40 of the ink holder 33 has a shape having a stepformed by the first holder section 37 and the second holder section 38that extend in the longitudinal direction (depth direction Y).

As illustrated in FIG. 3, an ink inlet 73 for injecting the ink into theink holder 33 is provided on the upper side 39 of the ink holder 33 in afirst part of the ink holder 33 that is situated outside the inkjetrecording device 11. In the first embodiment, the first holder section37 corresponds to the first part, and the ink inlet 73 is provided inthe first holder section 37. The ink inlet 73 can be covered with theslider 34 so that the ink inlet 73 that can be operated from the outsideof the inkjet recording device 11 is not exposed when the ink is notinjected.

Specifically, the slider 34 is formed to have an approximatelyrectangular external shape that extends in the longitudinal direction,and approximately completely overlaps the upper side 39 of the inkholder 33. The slider 34 is configured so that an openable cover 74covers the upper side of the ink inlet 73 provided to the ink holder 33when one end of the slider 34 is inserted into the frame member 23, andthe slider 34 approximately completely overlaps the upper side 39 of theink holder 33. Specifically, the slider 34 includes the openable cover74 that is provided at the end of the slider 34 in the longitudinaldirection, and is moved between a position that at which the openablecover 74 covers the ink inlet 73, and a position at which the ink inlet73 is exposed. Note that the term “insertion direction” used hereafterrefers to the insertion direction of the slider 34 into the frame member23 unless otherwise specified.

In the first embodiment, the openable cover 74 is pivotally supported bythe slider 34 around an axis that extends along the lateral direction ofthe ink holder 33 at a position away from the ink inlet 73 in thedirection of the second holder section 38 (second part) in a state inwhich the ink inlet 73 is covered. Therefore, the user can uncover theink inlet 73 by moving the front side of the openable cover 74 (situatedat the front end of the slider 34 in the longitudinal direction) upward,and rotating the openable cover 74 by about 180° toward the inkjetrecording device 11 (toward the second holder section 38) (see thetwo-dot chain line in FIG. 3).

Specifically, the openable cover 74 can be positioned on the rear sideof the ink inlet 73 by setting the openable cover 74 from a state inwhich the openable cover 74 covers the ink inlet 73 (see the solid linein FIG. 3) to a state in which the ink inlet 73 is exposed (see thetwo-dot chain line in FIG. 3). In the first embodiment, the ink inlet 73is provided in the vicinity of the front end of the first holder section37 of the ink holder 33 so that the length of the openable cover 74 inthe depth direction Y required to cover the ink inlet 73 does notincrease.

The ink container 21 illustrated in FIG. 3 also includes a connectionsection 43 that is connected to the inkjet recording device 11, arecording chip 75 (i.e., storage section), a chip holder 76 (i.e.,storage section-holding member), a protrusion 80 that is provided to thechip holder 76, a projection 82, a protrusion 93, a recess 95, a fingerplacement part 96 (for sliding the slider 34), and the like. Note thatthe ink container 21 according to the first embodiment need notnecessarily include these elements (shapes), and an appropriate elementmay be added, as required.

The internal configuration of the ink holder 33 is described below. Asillustrated in FIG. 4, the ink holder 33 includes a holder case 130 thatis formed approximately in the shape of the letter “L” when viewed inthe transverse direction X, a float valve 131 (i.e., valve mechanism)that is provided inside the holder case 130, a film 133 that is bonded(e.g., thermally welded) to the holder case 130 so as to cover a caseopening 132 of the holder case 130, and a cover 134 that is formed of aresin, and covers the case opening 132 through the film 133. The holdercase 130 is integrally formed so that the right side opens, and alocking part 130 a that locks a claw part 134 formed on the cover 134 isformed on the outer side of the ring-shaped case opening 132.

As illustrated in FIG. 5, when the film 133 is bonded to the holder case130 so as to cover the case opening 132 of the holder case 130, thespace enclosed by the holder case 130 and the film 133 functions as anair chamber 136 that communicates with the air, an ink chamber 137(i.e., liquid-holding chamber) that holds the ink, and a guide channel138 (i.e., liquid channel). Note that one end of the guide channel 138communicates with the ink chamber 137, and a guide outlet that guidesthe ink contained in the ink chamber 137 to the recording head 24(inkjet recording device 11) is formed on the other end of the guidechannel 138.

As illustrated in FIG. 5, the ink chamber 137 has a shape in which thedimension (height) of the front side in the vertical direction Z islarger than the dimension (height) of the rear side in the verticaldirection Z in the same manner as the ink holder 33. The ink chamber 137is divided into a first ink chamber 151 (i.e., first liquid chamber) anda second ink chamber 152 (i.e., second liquid chamber) by a partitionwall 150 that intersects a ceiling surface 137 b (i.e., inlet-formingsurface in which the ink inlet 73 is formed).

Note that the partition wall 150 extends along the vertical direction Z,and also intersects an opposing surface (bottom) 153 that is positionedopposite to the ceiling surface 137 b. The width of the partition wall150 in the transverse direction X is approximately equal to the width ofthe holder case 130 from a left sidewall 130 b to the case opening 132.The partition wall 150 is integrally formed with the holder case 130 ata front position within the ink chamber 137 at which the height in thevertical direction Z is large so as to perpendicularly intersect thesidewall 130 b of the holder case 130, and protrude from the sidewall130 b toward the case opening 132 (i.e., the front side in FIG. 5).Therefore, the height of the second ink chamber 152 in the verticaldirection Z at a position close to the first ink chamber 151 isapproximately equal to the height of the first ink chamber 151 in thevertical direction Z, and is larger than the height of the second inkchamber 152 in the vertical direction Z at a position away from thefirst ink chamber 151. The volume of the first ink chamber 151 issmaller than the volume of the second ink chamber 152.

Note that the first ink chamber 151 and the second ink chamber 152communicate with each other through a wall opening 156. Therefore, thepressure inside the first ink chamber 151 is almost equal to thepressure inside the second ink chamber 152, and the liquid surface ofthe ink contained in the first ink chamber 151 and the liquid surface ofthe ink contained in the second ink chamber 152 move upward in thevertical direction Z so as to have an approximately identical height.

As illustrated in FIG. 5, nine intersection ribs 157 a to 157 i (i.e.,at least one intersection rib) that intersect the ceiling surface 137 band extend along the vertical direction Z are formed in the second inkchamber 152 at an interval in the depth direction Y Diagonal ribs 158 ato 158 d (i.e., at least one eaves-like part) that intersect thevertical direction Z and the depth direction Y (horizontal direction)are also formed in the second ink chamber 152. Note that theintersection ribs 157 a to 157 i and the diagonal ribs 158 a to 158 dare integrally formed with the holder case 130 so as to perpendicularlyintersect the sidewall 130 b of the holder case 130, and protrude fromthe sidewall 130 b toward the case opening 132 (i.e., the front side inFIG. 5).

As illustrated in FIGS. 4 and 5, the first diagonal rib 158 a (i.e., thehighest diagonal rib) is formed to slope downward from the intersectionof the partition wall 150 and the ceiling surface 137 b toward the rearside. The second diagonal rib 158 a (i.e., the second highest diagonalrib) is formed to slope downward (gradually as compared with the firstdiagonal rib 158 a) from a position of the partition wall 150 lower thanthe first diagonal rib 158 a toward the rear side. Specifically, thefirst diagonal rib 158 a and the second diagonal rib 158 b are formed tointersect the partition wall 150 and intersect the depth direction Y.Note that the width of the first diagonal rib 158 a and the seconddiagonal rib 158 b in the transverse direction X is smaller than thewidth of the partition wall 150 and the intersection ribs 157 a to 157i. Therefore, when the film 133 is bonded to cover the case opening 132,a gap is formed between the first diagonal rib 158 a and the film 133and between the second diagonal rib 158 b and the film 133.Specifically, the spaces divided by the first diagonal rib 158 a and thesecond diagonal rib 158 b communicate each other through the gap.

The third diagonal rib 158 c (i.e., first eaves-like part) and thefourth diagonal rib 158 d (i.e., second eaves-like part) are formed onthe side of the bottom 152 a with respect to the second diagonal rib 158b at a position above the float valve 131. The third diagonal rib 158 cis formed between the partition wall 150 and the first intersection rib157 a, and the fourth diagonal rib 158 d is formed on the rear side withrespect to the second intersection rib 157 b. The third diagonal rib 158c and the fourth diagonal rib 158 d are formed so as to beline-symmetrical with respect to an axis (not illustrated in thedrawings) along the gravitational direction that passes through thecenter of the float valve 131, and slope downward from the center of thefloat valve 131 toward the end. Specifically, the distance between theupper end of the third diagonal rib 158 c and the upper end of thefourth diagonal rib 158 d is shorter than the distance of the lower endof the third diagonal rib 158 c and the lower end of the fourth diagonalrib 158 d.

Note that the width of the third diagonal rib 158 c and the fourthdiagonal rib 158 d in the transverse direction X is approximately equalto the width of the partition wall 150. Each end of the third diagonalrib 158 c and the fourth diagonal rib 158 d is formed to be recessedtoward the sidewall 130 b. Therefore, when the film 133 is bonded to thebonding surface (right end face) of the third diagonal rib 158 c and thefourth diagonal rib 158 d, the recess function as a rib communicationopening 161 that allows the ink to pass through. Specifically, thespaces divided by the third diagonal rib 158 c and the fourth diagonalrib 158 d communicate each other through the rib communication opening161.

A rib opening 160 is formed in the intersection ribs 157 a to 157 i.Therefore, an almost identical pressure develops in the spaces situatedon either side of each of the intersection ribs 157 a to 157 i.Therefore, the liquid surface of the ink contained in the second inkchamber 152 moves upward so as to have an approximately identical heightin the vertical direction Z.

As illustrated in FIG. 5, the guide flow channel 138 is formed along thebottom 152 a of the second ink chamber 152 at a position under thesecond ink chamber 152. The guide flow channel 138 includes a bentchannel 163 that is bent along the shape of the ink holder 33, andallows the ink composition to flow through while changing the flowdirection of the ink composition. The guide flow channel 138 alsoincludes a connection channel 164 that connects the second ink chamber152 and the bent channel 163, and a slope channel 165 that connects thebent channel 163 and the guide outlet 69.

The bent channel 163 includes two vertical channels 163 a and 163 b(i.e., at least one vertical channel) that extend along the verticaldirection Z, and four bent parts 173 a to 173 d (i.e., a plurality ofbent parts) that are formed on the end of the vertical channels 163 aand 163 b, and a horizontal channel 163 c that extends along the depthdirection Y

3.2. Second Embodiment

An ink container 200 according to the second embodiment is describedbelow with reference to FIG. 6.

FIG. 6 is a schematic cross-sectional view illustrating the inkcontainer 200 according to the second embodiment. The ink container 200is connected to a recording head 300 through an ink supply channel 400.

The ink container 200 includes an ink chamber 214 that has an air inlet212, and is configured so that air bubbles are formed in the inkcomposition by introducing air into the ink composition contained in theink chamber 214 through the air inlet 212. The ink container 200 has astructure in which the ink composition can come in contact with the air.The ink container 200 may have a structure in which the ink compositioncomes in contact with the air inlet 212 in a state in which the ink iscontained in the ink chamber 214 so that air bubbles are formed in theink composition by introducing air through the air inlet 212.

The inkjet recording device may include a plurality of ink containers200 (not illustrated in FIG. 6). The ink supply channel 400 may beformed of a material that exhibits flexibility (e.g., synthetic rubber),and may be a hose or a tube.

The ink composition supply method illustrated in FIG. 6 utilizes theprinciple of a Mariotte's bottle. Specifically, the recording head 300and the ink container 200 are connected through the ink supply channel400, and the ink composition is sucked from the ink container 200, andsupplied to the recording head 300.

FIG. 6 illustrates a state in which the ink container 21 is fitted intothe inkjet recording device in a usage state. The inkjet recordingdevice is placed on a horizontal plane sf. Note that the term “usagestate” used in connection with the inkjet recording device means thatthe inkjet recording device is in a state in which the inkjet recordingdevice can eject the ink composition toward the medium so that the inkcomposition normally adheres to the medium, and the inkjet recordingdevice need not necessarily be placed on a horizontal plane. An inkguide section 216 of the ink container 200 and the recording head 300are connected through the ink supply channel 400.

The outer side of the ink container 200 includes a first wall 270C1, asecond wall (upper wall) 270C2, and a bottom wall 270C3. The inkcontainer 200 includes an air introduction channel and an ink channel.The air introduction channel is a channel for introducing air into theink chamber 214 through an air opening 217, an air channel (notillustrated in FIG. 6), and an air inlet 218. An ink channel ink inlet204 is an opening for filling the ink chamber 214 with the inkcomposition through the ink channel ink inlet 204.

The air introduction channel is a channel used for the above airinduction operation. The air introduction channel includes the airopening 217 that opens to the outside (air), an air chamber 230 that isprovided with the air inlet 218 at one end, and provided with an airchamber-side opening 251 at the other end, and an ink chambercommunication channel 250 that is provided with the air chamber-sideopening 251 at one end, and provided with the air inlet 212 at the otherend. The air opening 217 communicates with the air, the air chamber 230opens at the air inlet 218 (i.e., one end), and the air opening 217 andthe air inlet 218 communicate with each other through a channel that isnot illustrated in FIG. 6. Specifically, the air chamber 230communicates with the outside (air). The air chamber-side opening 251(i.e., one end) of the ink chamber communication channel 250 opens intothe air chamber 230, and the air inlet 212 (i.e., the other end) of theink chamber communication channel 250 opens into the ink chamber 214.Specifically, the air chamber 230 communicates with the ink chamber 214.It is preferable that the ink chamber communication channel 250 have asmall cross-sectional area to such an extent that a meniscus (liquidsurface bridge) can be formed.

The air introduction channel is formed so that the air inlet 212 (i.e.,one end) opens into the ink chamber 214, and the air opening 217 (i.e.,the other end) opens to the outside. Specifically, a liquid surface thatcomes in direct contact with the air is formed in the ink chambercommunication channel 250 (in the vicinity of the air inlet 212) whenthe ink container 200 is in a usage state, and air (air bubbles) isintroduced into the ink contained in the ink chamber 214 from the airinlet 212 to introduce air (air bubbles G) into the ink chamber 214.This makes it possible to supply the ink composition from the inkcontainer 200 to the recording head 300 in a stable manner.

The ink supply operation is performed along with a reduction in theamount of ink stored in the ink container 200 due to ejection of the inkfrom the recording head 300, and is performed in a stable manner due tothe air introduction operation.

The state of the ink container 200 is classified into a usage state andan injection state. The term “usage state” used herein in connectionwith the ink container 200 refers to the state of the ink container 200when the inkjet recording device is in a usage state. The ink inlet 204opens in the horizontal direction when the ink container 200 is in theusage state. In this case, the opening of the ink inlet 204 is closed bya plug member 202. FIG. 6 illustrates the ink container 21 in the usagestate. The ink chamber 214 and the air chamber 230 are situated side byside in the horizontal direction when the ink container 21 is in theusage state. The air inlet 212 is situated at a position lower than theliquid surface of the ink composition contained in the ink chamber 214when the ink container 21 is in the usage state.

The term “injection state” used herein in connection with the inkcontainer 200 refers to a state in which the ink container 200 is placedso that the ink inlet 204 opens upward. The ink chamber 214 and the airchamber 230 are situated side by side in the vertical direction when theink container 21 is in the injection state. The air inlet 212 issituated at a position higher than the liquid surface of the inkcomposition contained in the ink chamber 214 (provided that the liquidsurface of the ink composition contained in the ink chamber 214 isindicated by a straight line LM1 (“first state display line LM1” (seeFIG. 6)) when the ink container 21 is in the usage state) when the inkcontainer 21 is in the injection state.

When the ink container 21 is in the injection state, the user may stopfilling the ink container 21 with the ink when the liquid surface of theink composition has reached the vicinity of a straight line LM2 (“secondstate display line LM2” (see FIG. 6)) that horizontally extends when theink container 21 is in the injection state. After the user has injectedthe ink composition into the ink chamber 214 from the ink inlet 204, theuser seals the ink inlet 204 using the plug member 202. The inkcontained in the ink chamber 214 is sucked from the recording head 300so that negative pressure develops in the ink chamber 214.

The air inlet 212 is situated at a position lower than the first statedisplay line LM1 when the ink container 21 is in the usage state. InFIG. 6, the air inlet 212 is formed in the bottom wall 270C3 of acontainer main body 211 (that defines the ink chamber 214) that issituated under the ink chamber 214 when the ink container 21 is in theusage state. This makes it possible to ensure that the liquid surface(air contact liquid surface) LA that comes in contact with the air ismaintained at a constant height for a long time (e.g., a time requiredfor the liquid surface of the ink composition to reach the first statedisplay line LM1), even when the ink contained in the ink chamber 214has been consumed, and the liquid surface of the ink compositioncontained in the ink chamber 214 has decreased. The air inlet 212 issituated at a position lower than the nozzle hole (not illustrated inFIG. 6) of the recording head 300 in the vertical direction when the inkcontainer 21 is in the usage state.

When the ink composition has been sucked from the recording head 300,and a predetermined negative pressure has developed in the ink chamber214, the ink composition contained in the ink chamber 214 is supplied tothe recording head 300 through the ink supply channel 400.

When the ink contained in the ink chamber 214 has been consumed, the aircontained in the air chamber 230 is introduced into the ink chamber 214as the air bubbles G through the ink chamber communication channel 250.Therefore, the liquid surface LF within the ink chamber 214 movesdownward. On the other hand, the height of the air contact liquidsurface LA that comes in contact with the air is maintained constant.

3.3. Shape of Ink Container

The ink container according to the first embodiment and the inkcontainer according to the second embodiment have a shape that satisfiesthe relationship “area of liquid surface at a filling ratio of 5%<areaof liquid surface at a filling ratio of more than 5%” when the inkcontainer is fitted into the inkjet recording device in the usage state,the filling ratio being the ratio of the volume of the ink composition(with which the ink container is filled) to the internal volume of theink container, and the liquid surface being the gas-liquid interface ofthe ink composition that is formed inside the ink container.

When the ink container has such a shape, gas may be dissolved in the inkcomposition. However, since air bubbles can be promptly removed from theink composition according to one embodiment of the invention, it ispossible to ensure that the inkjet recording device exhibits sufficientejection stability.

The ink container 21 according to the first embodiment may have such asize that the ink container 21 has a part in which the area of thegas-liquid interface of the ink composition that is formed inside theink container 21 is 10,000 mm² or more when the ink container 21 isfitted into the inkjet recording device in the usage state.

The ink container 21 according to the first embodiment and the inkcontainer 200 according to the second embodiment may have such a sizethat the ink container has a part in which the area of the gas-liquidinterface of the ink composition that is formed inside the ink containeris 900 mm² or more when the ink container is fitted into the inkjetrecording device in the usage state.

Since the ink container 21 according to the first embodiment that isformed in the shape of the letter “L” has a structure in which thesecond ink chamber 152 is connected to the connection channel 164 at alow position, it is possible to supply the ink composition in a stablemanner even when most of the ink composition contained in the inkcontainer 21 has been consumed. Therefore, it is possible to implement acontinuous recording operation in a stable manner, for example.

The ink container 21 according to the first embodiment may have such asize that the area of the gas-liquid interface of the ink compositionthat is formed inside the ink container 21 in a state in which the inkcontainer 21 is filled with the ink composition in a ratio of 95% withrespect to the internal volume of the ink container 21 is equal to orlarger than twice the area of the gas-liquid interface of the inkcomposition that is formed inside the ink container 21 in a state inwhich the ink container 21 is filled with the ink composition in a ratioof 5% with respect to the internal volume of the ink container 21 whenthe ink container 21 is fitted into the inkjet recording device in theusage state.

The ink container 200 according to the second embodiment may have such asize that the area of the gas-liquid interface of the ink compositionthat is formed inside the ink container 200 in the injection state islarger than the area of the gas-liquid interface of the ink compositionthat is formed inside the ink container 200 in the usage state in astate in which the ink container 200 is filled with the ink compositionin a ratio of 50% with respect to the internal volume of the inkcontainer 200. When the ink container has such a shape, it is possibleto reduce the installation area when the ink container is fitted intothe inkjet recording device. Moreover, since the ink container can beplaced in a more stable manner when filling the ink container in theinjection state with the ink composition, it is possible to fill the inkcontainer with the ink composition in a more stable manner.

4. Inkjet Recording System

An inkjet recording system according to one embodiment of the inventionincludes an ink composition that includes a disperse dye, and at leastone of a silicon-based surfactant and a fluorine-based surfactant, anink container that is provided with an ink inlet through which the inkcontainer can be refilled with the ink composition, and an inkjetrecording device that includes a recording head having a nozzle holethat ejects the ink composition, the ink composition having a surfacetension of 22 to 30 mN/m. The details of each element of the inkjetrecording system are the same as described above.

According to the inkjet recording system, since air bubbles can bepromptly removed from the ink composition when air bubbles have beenformed in the ink composition, it is possible to suppress a situation inwhich air bubbles remain in the inkjet recording system, and ensure goodejection stability.

5. Inkjet Recording Method

An inkjet recording method according to one embodiment of the inventionincludes: filling an ink container with an ink composition, the inkcomposition comprising a disperse dye, and at least one of asilicon-based surfactant and a fluorine-based surfactant, and having asurface tension of 22 to 30 mN/m, and the ink container being providedwith an ink inlet through which the ink container can be refilled withthe ink composition; fitting the ink container into an inkjet recordingdevice that includes a recording head having a nozzle hole that ejectsthe ink composition; and ejecting the ink composition from the nozzlehole so that the ink composition adheres to a medium.

The medium is not particularly limited. Examples of the medium includepaper, a film, a cloth, an actual printing stock, a metal, glass, apolymer, and the like. The medium may be colorless and transparent,translucent, colored and transparent, chromatic and opaque, achromaticand opaque, or the like.

The inkjet recording method according to one embodiment of the inventionmay be applied to printing. For example, the inkjet recording methodaccording to one embodiment of the invention may be applied tosublimation transfer printing since the disperse dye has sublimationproperties. The inkjet recording method according to one embodiment ofthe invention may be applied to printing (direct sublimation printing)that utilizes a fabric cloth or the like as the medium. The inkjetrecording method according to one embodiment of the invention mayinclude a transfer step, a heating step, a steaming step, and the likecorresponding to the printing method.

Since the inkjet recording method according to one embodiment of theinvention fills the ink container with the ink composition, fits the inkcontainer into the inkjet recording device, and ejects the inkcomposition so that the ink composition adheres to the medium, airbubbles can be promptly removed from the ink composition when airbubbles have been formed in the ink composition. Therefore, it ispossible to ensure good ejection stability during inkjet recording, andimplement a good recording process that can reliably form the entireimage on the medium, for example.

6. Examples and Comparative Examples

The invention is further described below by way of examples andcomparative examples. Note that the invention is not limited to thefollowing examples.

6.1. Preparation of Ink Composition

The ink compositions of the examples and the comparative examples wereprepared using the components shown in Table 1.

The details of the components shown in Table 1 are as follows. KayasetRed B (manufactured by Nippon Kayaku Co., Ltd.) was used as Disperse Red60 (disperse dye), and Oil Yellow 54 (manufactured by Chuo SyntheticChemical Co., Ltd.) was used as Disperse Yellow 54 (disperse dye).

BYK-348 (manufactured by BYK Japan KK), Surflon S-211 (manufactured byAsahi Glass Co., Ltd.), and Surfynol 104PG50 (manufactured by NissinChemical Co., Ltd.) (acetylene glycol-based surfactant) were used as thesurfactant either alone or in combination.

Lavelin (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) (formaldehydecondensate of sodium methylnaphthalenesulfonate) was used as thedispersant.

Triethylene glycol monomethyl ether, triethylene glycol monobutyl ether,and 1,2-hexanediol (reagent) were used as the penetrant either alone orin combination. Glycerol and triethanolamine (reagent) were used as theadditional additive. Note that the HLB value of each penetrant shown inTable 1 was calculated using the expression “HLB value=10×(IV/OV)” (see“1.3.3. Penetrant”).

After the addition of ion-exchanged water (balance) to a mixture ofthese components to adjust the content (mass %) of each component asshown in Table 1, the resulting mixture was stirred for 2 hours using amagnetic stirrer, and filtered through a membrane filter having a poresize of 5 micrometers to prepare each ink composition.

The surface tension of the resulting ink composition was measured usinga surface tensiometer (“CBVP-Z” manufactured by Kyowa Interface ScienceCo., Ltd.). The results are shown in Table 1.

TABLE 1 Example 1 2 3 4 5 6 7 Disperse dye Disperse Red 60 5 — 5 — 5 5 —Disperse Yellow 54 — 3 — 3 — — 3 Dispersant Lavelin AN-40 7.5 4.5 7.54.5 7.5 7.5 7.5 Surfactant BYK348 0.75 0.5 0.3 0.1 0.75 0.75 — SurflonS211 — — — — — — 0.1 Surfynol 104PG50 — — — — — — — PenetrantTriethylene glycol 3 5 3 3 3 3 3 monomethyl ether (HLB = 19.3)Triethylene glycol — — — — 1 — — monobutyl ether (HLB = 13.5)1,2-Hexanediol — — — — — 0.3 0.3 (HLB = 16.7) Additional additiveGlycerol 15 15 15 15 15 15 15 Triethanolamine 0.5 0.5 0.5 0.5 0.5 0.50.5 Water Balance Balance Balance Balance Balance Balance BalanceSurface tension (mN/m) 25 22 29 27 25 25 25 Evaluation results Ejectionstability A A B B A A A Ink storage stability A A A A A A A ExampleComparative Example 8 9 1 2 3 4 Disperse dye Disperse Red 60 5 5 5 5 5 5Disperse Yellow 54 — — — — — — Dispersant Lavelin AN-40 7.5 7.5 7.5 7.57.5 7.5 Surfactant BYK348 0.75 0.1 0.1 — — — Surflon S211 — 0.1 — 1 — —Surfynol 104PG50 — — — — 1 1 Penetrant Triethylene glycol 3 3 — — — —monomethyl ether (HLB = 19.3) Triethylene glycol 2.5 — — — — — monobutylether (HLB = 13.5) 1,2-Hexanediol — — — — — 5 (HLB = 16.7) Additionaladditive Glycerol 15 15 15 15 15 15 Triethanolamine 0.5 0.5 0.5 0.5 0.50.5 Water Balance Balance Balance Balance Balance Balance Surfacetension (mN/m) 25 24 31 18 27 25 Evaluation results Ejection stability AA C C B B Ink storage stability B A A A B C

6.2. Evaluation Methods 6.2.1. Ejection Stability

A dedicated cartridge (ink container) of an inkjet recording device“PX-H6000” (manufactured by Seiko Epson Corporation) was filled witheach ink composition shown in Table 1. The ink container was fitted intothe inkjet recording device (“PX-H6000”) as a yellow cartridge. Notethat the ink container used for evaluation had an ink inlet throughwhich the ink container can be refilled with the ink composition, andhad a shape that satisfies the relationship “area of liquid surface at afilling ratio of 5%<area of liquid surface at a filling ratio of morethan 5%” when the ink container is fitted into the inkjet recordingdevice in the usage state.

The nozzle hole of the inkjet recording device (“PX-H6000”) had a shapein which the area of the cross section of the nozzle hole perpendicularto the ink composition ejection direction decreased discontinuously inthe ink composition ejection direction.

The ink composition was ejected toward premium glossy photo paper (PGPP)(manufactured by Seiko Epson Corporation) to continuously obtain thirtysheets of paper on which a solid pattern image was printed. The numberof missing parts within the image was counted, and the ejectionstability was evaluated in accordance with the following standard. Theevaluation results are shown in Table 1.

-   -   A: The number of missing parts was 0.    -   B: The number of missing parts was 1 to 30.    -   C: The number of missing parts was 31 or more.

6.2.2. Storage Stability

The ink container that was filled with each ink composition as describedabove (see “6.2.1. Ejection stability”) was allowed to stand at 60° C.for 1 week. The ink composition was then removed from the ink container,and the viscosity of the ink composition, and the average particle sizeof the disperse dye were measured. The viscosity of the ink compositionwas measured at 20° C. using a viscoelasticity tester “MCR-300”(manufactured by Pysica) while increasing the shear rate from 10 to1000. The viscosity when the shear rate was 200 was taken as theviscosity of the ink composition. The particle size D50 (i.e., theparticle size at 50% in the cumulative volume average particle sizedistribution) of the disperse dye measured using a device “MicrotracUPA” (manufactured by Nikkiso Co., Ltd.) was taken as the averageparticle size of the disperse dye.

The viscosities and the average particle sizes measured before and afterstorage were compared, and the storage stability was evaluated inaccordance with the following standard. The evaluation results are shownin Table 1.

-   -   A: A change in viscosity or a change in average particle size        was less than 5%.    -   B: A change in viscosity or a change in average particle size        was 5% or more and less than 10%.    -   C: A change in viscosity or a change in average particle size        was less than 10% or more.

6.3. Evaluation Results

Excellent ejection stability was achieved when using the inkcompositions of Examples 1 to 9 having a surface tension of 22 to 30mN/m. Particularly excellent ejection stability was achieved when usingthe ink compositions of Examples 1, 2, and 5 to 9 having a surfacetension of 22 to 25 mN/m. On the other hand, ejection stability wasinsufficient when using the ink compositions of Comparative Examples 1and 2 having a surface tension falling outside the range of 22 to 30mN/m.

Since excellent ejection stability was achieved when using the inkcompositions of Examples 1 to 9 even when the ink container had an inkinlet through which the ink container can be refilled with the inkcomposition, and had a shape that satisfies the relationship “area ofliquid surface at a filling ratio of 5%<area of liquid surface at afilling ratio of more than 5%” when the ink container is fitted into theinkjet recording device in the usage state, and the nozzle hole had apart in which the area of the cross section of the nozzle holeperpendicular to the ink composition ejection direction decreasesdiscontinuously in the ink composition ejection direction, it isconsidered based on the above results that the ink compositions ofExamples 1 to 9 had a high capability to remove (discharge) air bubbles.

The ink compositions of Examples 1 to 9 including a penetrant having anHLB value of 17 to 30 exhibited sufficient storage stability. However,the ink composition of Example 8 having a penetrant content of more than1 mass % showed a slight deterioration in storage stability. When usingthe ink compositions of Comparative Examples 3 and 4 including theacetylene glycol-based surfactant, ejection stability and storagestability were insufficient although the surface tension was within therange of 22 to 30 mN/m. When using the ink composition of ComparativeExample 4 including the penetrant having an HLB value of less than 17 ina ratio of 5 mass %, ejection stability was not improved as comparedwith Comparative Example 3, and storage stability was insufficientalthough the surface tension was 25 mN/m.

The invention is not limited to the above embodiments, and variousmodifications and variations may be made of the above embodimentswithout departing from the scope of the invention. For example, theinvention includes various other configurations that are substantiallythe same as the configurations described in connection with the aboveembodiments (e.g., a configuration having the same function, method, andresults, or a configuration having the same objective and results). Theinvention also includes a configuration in which an unsubstantial partdescribed in connection with the above embodiments is replaced byanother part. The invention also includes a configuration having thesame effects as those of the configurations described in connection withthe above embodiments, or a configuration capable of achieving the sameobjective as that of the configurations described in connection with theabove embodiments. The invention further includes a configuration inwhich a known technique is added to the configurations described inconnection with the above embodiments.

REFERENCE SIGNS LIST

1: nozzle plate, 2: nozzle hole, 3: boundary part, 4: ejectiondirection, 5: accumulation part, 11: inkjet recording device, 12: wheel,13: leg, 14: main body, 15: feeder, 16: housing, 17: inlet, 18: outlet,19: medium-receiving unit, 20: operation panel, 21: ink container, 22:ink container unit, 23: frame member, 24: recording head, 25: carriage,33: ink holder, 34: slider, 37: first holder section, 38: second holdersection, 39: upper side, 40: lower side, 41, 42: flat section, 43:connection part, 69: guide outlet, 73: ink inlet, 74: openable cover,75: chip, 76: chip holder, 80: protrusion, 82: projection, 93:protrusion, 95: recess, 96: finger placement part, 130: holder case, 130a: locking part, 130 b: sidewall, 131: float valve, 132: case opening,133: film, 134: cover, 134 a: claw part, 136: air chamber, 137: inkchamber, 137 b: ceiling surface, 138: guide flow channel, 150: partitionwall, 151: first ink chamber, 152: second ink chamber, 152 a: bottom,153: opposing surface, 156: wall opening, 157 a to 157 i: intersectionrib, 158 a to 158 d: first to fourth diagonal ribs, 160: rib opening,161: rib communication opening, 163: bent channel, 163 a, 163 b:vertical channel, 163 c: horizontal channel, 164: connection channel,165: slope channel, 173 a to 173 d: bent part, 200: ink container, 202:plug member, 204: ink inlet, 211: container main body, 212: air inlet,214: ink chamber, 216: ink guide section, 217: air opening, 218: airinlet, 230: air chamber, 250: ink chamber communication channel, 251:air chamber-side opening, 270 c 1: first wall, 270 c 2: second wall, 270c 3: bottom wall, 300: recording head, 400: ink supply channel, R: roll,S: paper, sf: horizontal plane, G: air bubble

1. An ink composition that is held in an ink container that is providedwith an ink inlet through which the ink container can be refilled withthe ink composition, and is used in a state in which the ink containeris fitted into an inkjet recording device that includes a recording headhaving a nozzle hole that ejects the ink composition, the inkcomposition comprising a disperse dye, and at least one of asilicon-based surfactant and a fluorine-based surfactant, the inkcomposition having a surface tension of 22 to 30 mN/m.
 2. The inkcomposition according to claim 1, the nozzle hole having a part in whichan area of a cross section of the nozzle hole perpendicular to an inkcomposition ejection direction decreases discontinuously in the inkcomposition ejection direction.
 3. The ink composition according toclaim 1, the ink container satisfying a relationship “area of liquidsurface at a filling ratio of 5% <area of liquid surface at a fillingratio of more than 5%” when the ink container is fitted into the inkjetrecording device in a usage state, the filling ratio being a ratio of avolume of the ink composition with which the ink container is filled toan internal volume of the ink container, and the liquid surface being agas-liquid interface of the ink composition that is formed inside theink container.
 4. The ink composition according to claim 1, the inkcomposition having a surface tension of 22 to 25 mN/m.
 5. The inkcomposition according to claim 1, further comprising a penetrant havingan HLB value of 17 to
 30. 6. The ink composition according to claim 1,comprising a penetrant having an HLB value of less than 17 in a ratio of1 mass % or less based on a total amount of the ink composition.
 7. Aninkjet recording system comprising: an ink composition that comprises adisperse dye, and at least one of a silicon-based surfactant and afluorine-based surfactant; an ink container that is provided with an inkinlet through which the ink container can be refilled with the inkcomposition; and an inkjet recording device that includes a recordinghead having a nozzle hole that ejects the ink composition, the inkcomposition having a surface tension of 22 to 30 mN/m.
 8. An inkjetrecording method comprising: filling an ink container with an inkcomposition, the ink composition comprising a disperse dye, and at leastone of a silicon-based surfactant and a fluorine-based surfactant, andhaving a surface tension of 22 to 30 mN/m, and the ink container beingprovided with an ink inlet through which the ink container can berefilled with the ink composition; fitting the ink container into aninkjet recording device that includes a recording head having a nozzlehole that ejects the ink composition; and ejecting the ink compositionfrom the nozzle hole so that the ink composition adheres to a medium.